lar tree size per orchard and segregated data 

 according to sampling dates before, between, 

 and after insecticide applications. The data 

 (Table 1) show that no fruit injury was detected 

 prior to the first insecticide application even 

 though some curculio captures by traps in each 

 position had occurred. For none of the trap po- 

 sitions in any block type (i.e. tree-size type) was 

 there a significant positive relationship between 

 mean number of captured adults per block and 

 mean number of sampled fi-uit injured per block. 

 This was true for sampling data between the 

 first and second insecticide application, between 

 the second and third insecticide application, and 

 following the last insecticide application. In 

 every block type, mean ft-uit injury increased 

 between the first and second, between the sec- 

 ond and third, and after the third insecticide 

 application. Conversely, in most cases, mean 

 trap captures either successively decreased 

 fi-om levels that were reached prior to any in- 

 secticide treatment or were nil throughout. 



The greatest fruit injury in any of the 48 

 blocks was in a block of large trees in Orchard 

 D (a mean of 2.5% fruit injured). Not a single 

 plum curculio was captured by any trap in this 

 block. Conversely, in the two blocks receiving 

 the greatest trap captures (small trees in Or- 



chard D and large trees in Orchard F), there 

 were means of only 0.24 and 0.19% injured fi*uit, 

 respectively. Most blocks received injury greater 

 than this. 



Conclusions 



Data from this study in eight large commer- 

 cial apple orchards in 1997 are in agreement 

 with data ft-om our 1996 study in a single small 

 orchard and do not support the use of captures 

 of plum curculio adults by unbaited black pyra- 

 mid traps as accurate predictors of the need to 

 apply insecticide against curculio. This conclu- 

 sion holds irrespective of the position at which 

 unbaited pyramid traps were placed in an or- 

 chard. For the future, we need either a differ- 

 ent type of trap or a powerful attractive odor to 

 enhance the value of black pyramid traps. In 

 succeeding articles in this issue, we describe 

 progress toward developing alternative types 

 of traps and attractive odors to incorporate into 

 traps. 



Acknowledgments 



This work was supported by grants fi-om the 



Fruit Notes, Volume 63 (Number 1), Winter, 1998 



